The present invention relates to a fixing apparatus for use in an image forming apparatus such as a copying machine, printer, facsimile device, etc., and more particularly, to a fixing apparatus capable of starting quickly.
Conventionally, as a fixing apparatus for use in an image forming apparatus such as a copying machine, a printer, a facsimile device, or the like, a heat roller fixing type device is widely adopted from a low speed apparatus to a high speed apparatus, and from a monochromatic apparatus to a full-color apparatus, as the fixing apparatus which has the high technical complication degree and stability.
However, in the conventional heat roller fixing type fixing apparatus, when transfer material or toner is heated, it is necessary that a fixing roller having a large thermal capacity is heated, therefore, the effect of energy conservation is not good, and it is disadvantageous to the phase of the energy conservation, and when printing, it takes a long period of time to warm up the fixing apparatus, therefore the print time (warming up time) takes a long period of time, which is a problem.
In order to solve these problems, a film fixing type fixing apparatus in which a film (heat fixing film) is used, and the thickness of the heat roller is decreased to that of heat fixing film which is the ultimate thickness and the thermal capacity of the heat roller is decreased, and heat conduction efficiency is greatly improved by directly pressure-contacting the temperature controlled-heater (ceramic heater) onto the heat fixing film, and the energy conservation and the quick start which requires almost no warming-up time are intended, and an image forming apparatus therewith are proposed and used recently.
Further, a fixing method in which, as a variation of the heat roller, a ray-transmitting base member is used as a ray radiating roller (a rotary member for applying heat), and a ray from a halogen lamp (ray radiating means) provided inside the heat roller is radiated on toner for heat fixing, and the quick start which requires almost no warming-up time, is intended, is disclosed in Japanese Tokkaisho No. 52-106741, No. 57-82240, No. 57-102736, No. 57-102741, etc. Further, a fixing method, in which a ray absorbing layer is provided on outer peripheral surface of the ray-transmitting base member and thereby, the ray irradiating roller (a rotary member for applying heat) is structured, and a ray from a halogen lamp (ray radiating means) provided inside the cylindrical ray-transmitting base member is absorbed in the ray absorbing layer provided on the outer peripheral surface of the ray-transmitting base member, and the toner image is fixed by the heat of the ray-absorbing layer, is disclosed in Japanese Tokkaisho No. 59-65867.
However, in the fixing apparatus disclosed in Japanese Tokkaisho No. 52-106741, the quick start wherein energy conservation and reduction of warming-up time are attained is intended through a method to heat and fix toner by irradiating through a ray-transmitting base member with a ray from a halogen lamp (ray radiating means), while, in the fixing apparatus disclosed in Japanese Tokkaisho No. 59-65867, the quick start is intended through a method in which a light absorbing layer (ray absorbing layer) is provided on outer peripheral surface of the ray-transmitting base member, thereby, the ray irradiating roller (a rotary member for applying heat) is structured, and a ray from a halogen lamp (ray radiating means) is radiated through the ray-transmitting base member onto the ray absorbing layer, so that the toner is fixed by the heat of the ray-absorbing layer, the energy conservation and the quick start in which the warm-up time is reduced. However, the method using only heat generation from the ray absorbing layer on the surface has problems that the temperature of the lower portion of the ray absorbing layer is low, and the temperature of the ray absorbing layer suddenly falls when making prints, and the hysteresis on the portion where a transfer material passes remains for a long time, causing temperature fluctuation on the rotary member for applying heat, although the warming-up time can be shortened.
Further, since a cylindrical glass member is used mainly as a material of the ray-transmitting base member, there are caused problems that the cylindrical accuracy (circularity and cylindricity of an outer circumferential cylinder) of the ray-transmitting base member is poor, and thereby, pressure force and rotation of a rotary member for applying heat lack evenness, which tends to cause uneven fixing.